The invention relates to a machining tool for machining materials by removing material, in particular for wood or wood-like materials, metals, plastics and/or composite materials, provided for rotary drive action about an axis of rotation, comprising at least one row, arranged in circumferential direction, of individual cutters with cutting edges that at least partially overlap each other, wherein the cutting edges have a wedge angle and are positioned at an axial angle relative to the axis of rotation.
When machining materials by removing material, a rework-free smooth surface is desired for which purpose the geometry of the cutting edge of the machining tool must be optimized. However, in particular when machining wood or wood-like materials, different disadvantageous effects can be observed which impair the quality of the machined surface. When machining wood, so-called pre-splitting occurs, for example. When removing a chip in the direction of the fibers, a crack, referred to as pre-splitting, runs ahead of the cutter. This facilitates machining and extends the tool life of the cutter; however, it also results in an undesirable rough surface. Moreover, it can happen that the material fibers stand up again after cutting.
In order to achieve, despite these effects, a rework-free surface as smooth as possible, the cutting edge of the tool must have little cutting edge rounding and a small wedge angle. However, in particular the wedge angle is subject to the limitation that, for various cutter materials, it must not fall below a given value. If the wedge angle is too small, blunting of the cutting edge occurs already at the beginning of the machining process along with an increase of the cutting edge rounding, and/or chipping at the cutting edge occurs with the result that the required cutting quality is not achieved.
Another influencing factor is the material to be machined. For example, in the case of the wood species meranti used in particular for window frames, wear on the cutting edge occurs which is approximately fifty times the wear compared to the cutting edge wear when machining spruce.
Thus, in order to use a wedge angle which, for reasons of wear, on the one hand, is not too small and to use a wedge angle which, for reasons of surface quality, is not too great, high-speed steels with wedge angles between 30° and 45° and carbides with wedge angles between 40° and 55° can usually be used. Harder cutter materials with greater wedge angles cannot be used.
Another influencing factor for influencing the cutting results is the axial angle at which the cutting edge is arranged relative to the rotational axis or its direction of rotational movement. According to the prior art, it is considered to be problematic that, due to the angular position of the cutters, reaction forces occur not only in the direction of rotational movement but also perpendicular thereto in the axial direction. In order to solve this problem, WO 2008/113314 A1 describes a cylindrical milling cutter on which hard metal inserts are aligned section-wise at different axial angle in such a manner that the axial forces generated during the milling process in the different sections at least approximately cancel each other out. However, this does not solve the problem of cutter wear and surface quality so that cutters with the usual wedge angles within the above described limits have to be used.
The object of the invention is to develop further a machining tool of the aforementioned kind in such a manner that despite achieving an improved surface result, a reduced wear occurs.